Hi John,
Regarding the NDMP part of your email:
We're also thinking of finally making the move to NDMP as well from
NFS backups, but we're quite concerned about the limitations of DAR
(Direct Access Restore) allowing us to restore large chunks of NDMP
backups without having to manually break it into chunks due to
Networker/NetApp limits?
Our environment (Solaris 8, v7.2.2) is solid, but badly in need of an
upgrade (AIT-2 tapes and drives are overwhelmed by our 15TB of storage).
That said, I believe the comments are valid in general.
The best thing about NDMP is that it really sped up backups since the
data bypasses the server. We have a 1.5TB saveset that went from 5-14
days (NFS) to 2-3 days (NDMP).
Here are the gotcha's I've found so far with NDMP:
(1) The biggest problem is lack of multiplexing by default. If you have
3 tape drives, you can only have 3 savesets backing up. So, you need to
stagger the groups/savesets to make sure each one has its own tape drive
during the backup
(1a) v7.2.2 allows multiplexing via the "-M" option to the "dump" command
(we haven't incorporated "-M" into our backup scheme yet, so I can't
comment on it)
(2) via the "recover" command, you can restore only 10,000 files at a
time on a netapp (so you have to do either multiple "recover" sessions
or a saveset recover)
(3) you can't read directly off a tape written using ndmp (there's no
equivalent to the "uasm" functionality).
(3a) This fact becomes important when you want to restore 10K+ files on
a netapp.
(3b) If your indexes are gone (we had a bleeding-edge filestorage unit
whose indexes often failed to backup), know the command-line incantation:
"nsrndmp_recover -c client -m destination -S ssid -v off path_to_recover"
("-m destination" means non-destructive recover, "-v off" means no indexes)
(3c) for restores where you have to read off the tape, you definitely
want the smallest possible savesets for ndmp
(4) if you backup from a netapp, you can only restore to a netapp. I'm
looking forward to testing the "-M" option since it allows you to
restore to the server (you don't have to restore to the netapp)
Please correct me if I have mis-represented anything - it's been trial &
error understanding the limitations of ndmp.
-Elena
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